1. Field of the Invention
The present invention relates to a radiation image imaging apparatus, and particularly, to a radiation image imaging apparatus that converts an irradiated radiation into image data, and reads out the image data.
2. Description of the Related Art
There have been developed a variety of radiation image imaging apparatuses, each of which converts an irradiated radiation such as an X-ray into other-wavelength light such as visible light by a scintillator, thereafter, generates electric charges in a photoelectric conversion element such as a photodiode in response to energy of the converted and irradiated light, and coverts the radiation into an electric signal (that is, image data).
This type of radiation image imaging apparatus is known as a flat panel detector (FPD), and heretofore, has been composed as a so-called dedicated type (also referred to as a fixed type) (for example, refer to Japanese Patent Application Laid-Open Publication No. H09-73144 (published in 1997)), which iis formed integrally with a supporting base. However, in recent years, a portable-type radiation image imaging apparatus, which has a photoelectric conversion element and the like housed in a cabinet thereof and is made portable, has been developed and put into practical use (for example, refer to Japanese Patent Application Laid-Open Publication No. 2006-058124 and Japanese Patent Application Laid-Open Publication H06-342099 (published in 1994).
In usual, the radiation image imaging apparatus is composed in such a manner that a plurality of photoelectric conversion elements are arrayed in a two-dimensional shape (matrix shape) on a sensor board, and that switch units formed of thin film transistors (hereinafter, referred to as TFTs) and the like are individually connected to the respective photoelectric conversion elements. The switch units are individually connected to scan lines, turn to an OFF state when being applied with an OFF voltage from the scan lines, and accumulate electric charges in the photoelectric conversion element. Moreover, when being applied with an ON voltage from the scan lines, the switch units discharge the electric charges accumulated in the photoelectric conversion element.
Then, in usual, radiation image imaging is performed in such a manner that the radiation is irradiated onto the radiation image imaging apparatus from a radiation source of a radiation generation apparatus in a state of transmitting through a predetermined imaging target region (that is, a front surface of a breast, a side surface of a lumbar, or the like) of a body of subject, or the like. During the irradiation of the radiation, the switch units of the photoelectric conversion elements are turned to the OFF state, the irradiated radiation is converted into light by the scintillator, the converted light is irradiated onto the photoelectric conversion element, and electric charges generated in the photoelectric conversion elements by the irradiation of the light (that is, the irradiation of the radiation) are accumulated in the photoelectric conversion elements.
Then, when the ON voltage is applied from the scan lines to the switch units, the electric charges accumulated in the photoelectric conversion elements are sequentially discharged to signal lines, and the electric charges are converted into image data D by a reading circuit connected to the signal lines, and the respective pieces of the image data 13 are individually read out. In usual the radiation image imaging apparatus is configured so as to perform reading processing as described above.
Incidentally, it is known that, when impacts and vibrations are applied from the outside to the radiation image imaging apparatus in the event of the reading processing for the image data D, or the like, which is as described above, then in some case, a relatively large noise is superimposed on the image data D, which are read out from the respective photoelectric conversion elements, and image quality is deteriorated. Then, though a cause that the noise as described above occurs is not always clearly turned out, the cause is conceived to result from static electricity generated on the periphery of the sensor board on which the respective photoelectric conversion elements are formed.
Accordingly, for the purpose of preventing such a phenomenon from occurring, for example, Japanese Patent Application Laid-Open Publication No. 2010-19620 proposes that an anti-static layer is provided between the sensor board and the scintillator. This is a measure for preventing an occurrence of a so-called image defect since the photoelectric conversion elements are broken owing to the static electricity to be generated in the case of pasting things with a relatively large area, such as the sensor board and the scintillator, onto each other, or peeling off these things from each other. In the case of providing the anti-static layer as described above, it becomes possible to suppress the occurrence of the static electricity at least in comparison with the case of not providing the anti-static layer, and it becomes possible to reduce an occurrence of the image defect.
Therefore, it is conceived that use of such a technology is useful also for preventing an occurrence of the above-described phenomenon that the noise is superimposed on the image data D, which are to be read out, when the impacts and the vibrations are applied to the radiation image imaging apparatus in a state where the static electricity is generated on the periphery of the sensor board.
Moreover, for example, Japanese Patent Application Laid-Open Publication No. 2011-58999 illustrates a configuration in which a radiation shielding sheet, a heat insulating sheet, a conductive shield member and an electric processing unit are arranged in this order on a surface side of the sensor board, which is opposite with the scintillator. This is a configuration for preventing the noise, which occurs on one side, from transmitting to other side in such a manner that such an electric noise, which occurs on the sensor board side and the electric processing unit side, is shielded and received by the shield member, and is let go through a shield finger to a cabinet, and so on.
However, in accordance with researches of the inventors of the present invention, it is gradually understood that, in some cases, there cannot be sufficiently prevented the occurrence of the above-described phenomenon that the noise is superimposed on the image data D at least by the fact that the impacts and the vibrations are applied to the radiation image imaging apparatus if the anti-static layer is only provided between the sensor board and the scintillator, for example, as described in Japanese Patent Application Laid-Open Publication No. 2010-19620.
Moreover, it is gradually understood that the occurrence of the static electricity cannot be always prevented sufficiently even if such a configuration as described in Japanese Patent Application Laid-Open Publication No. 2011-58999 described above is adopted, and in some case, the occurrence of the phenomenon that the noise is superimposed on the image data D at least by the fact that the impacts and the vibrations are applied to the radiation image imaging apparatus cannot be surely prevented.
Moreover, the following is gradually understood. Specifically, also in the case of adopting a configuration so that start of the radiation irradiation can be detected by the radiation image imaging apparatus itself without depending on a signal from the radiation generation apparatus side that irradiates the radiation onto the radiation image imaging apparatus concerned, in the case where the impacts and the vibrations are applied to the radiation image imaging apparatus when the static electricity is generated on the periphery of the sensor board in the event of detection processing of the start of the radiation irradiation, the start of the radiation irradiation is sometimes detected erroneously.